Compliant pins are now being used in vast numbers in the electronics industry when it is necessary to establish contact with the conductors in a multi-layer board, a back panel, or a simple circuit board having a plated through hole. A compliant contact pin has a compliant portion which has a normal width which is greater than the hole diameter but which can be deformed when it moves into the circuit board hole so that contact edge portions of the compliant portion will establish the electrical contact required with the conductors in the circuit board hole. The compliant portion thus is essentially a relatively stiff spring system which, after insertion into the circuit board hole, will bear against the surfaces of the hole with sufficient force to retain the pin in the circuit board and to establish a sound electrical contact with the circuit board conductors. Some commonly known types of compliant pins are shown, for example, in U.S. Pat. Nos. 4,186,982, 4,743,081, 4,206,964, and 4,606,589.
Notwithstanding the fact that compliant pins are presently being used in large numbers, there are many circumstances under which it would be desirable to employ compliant pin technology but in which it is not now feasible to do so for the reason that most of the presently known types of compliant pins lack adaptability in the sense that the compliant pin must be manufactured from metal stock having some minimum thickness and the pin will not perform adequately if an attempt is made to manufacture the pin from a stock metal which is thinner than the required minimum. For example, a widely used standard sized hole for circuit boards or other panel-like members in which contact pins are mounted is 0.040 inches (1.02 mm). Many of the presently available compliant pins are manufactured from metal stock having a thickness of 0.025 inches (0.63 mm) if the pin is intended for insertion into a 0.040 inch diameter hole. Some presently available compliant pins can be produced from metal stock having a thickness of 0.015 inches (0.38 mm) but with some sacrifice of performance. Presently available contact pins thus have only limited adaptability insofar as the hole diameter and stock thickness relationships are concerned.
There are many circumstances where a contact pin must be inserted into a 0.040 inch (1.02 mm) diameter hole but where it is impossible to use 0.025 inch thick stock or even 0.015 inch (0.38 mm) stock for the pin. Manufacturing cost considerations alone may limit the thickness of the stock to 0.012 inches (0.30 mm) or less. The stock thickness for a contact pin may also be limited if the contact pin is integral with a spring receptacle or the like which must, for mechanical reasons, be manufactured from relatively thin stock metal. Circuit board switches such as DIP switches, for example, contain spring contacts which must be manufactured from extremely thin stock metal, say 0.008 inches (0.20 mm). It would be desirable if the pin portion of the spring contacts could be provided with a compliant portion so that the DIP switch could be mounted on the circuit board by merely inserting the contact pins which extend from the switch housing into circuit board holes. At present, if the circuit board hole size is the standard 0.040 inches as noted above, and if the spring contact is of relatively thin material, the connector or switch must be connected to the circuit board conductors by conventional soldering methods with a significant increase in assembly cost over comparable compliant pin assembly methods.
Some reduction in the stock thickness of a compliant pin might be obtained if special manufacturing techniques such as coining are resorted to, but such techniques would increase manufacturing cost. The preferred method of manufacturing compliant pins is by simple stamping and forming methods.
The present invention is directed to the achievement of an improved compliant pin which has a wide range of adaptability in the sense that the pin can be manufactured from metal stock having a wide thickness range. The invention is also directed to the achievement of a compliant pin which can be manufactured by conventional known stamping and forming methods and which does not require highly critical and sensitive metal working steps in its production.